Refactoring of queue/queue-policy:

- moved some logic out of Queue.cpp into QueuePolicy.cpp
- moved QueuedMessage definition into its own header file
- added checks for requeue and dequeue
- split QueuePolicy logic into different sub classes
Added ability to request old messages to be discareded to make room for new ones when configured limit has been reached.



git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@697603 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 168 insertions, 15 deletions

diff --git a/cpp/src/qpid/broker/QueuePolicy.cpp b/cpp/src/qpid/broker/QueuePolicy.cpp
index 08838aac79..8aeaaabd55 100644
--- a/cpp/src/qpid/broker/QueuePolicy.cpp
+++ b/cpp/src/qpid/broker/QueuePolicy.cpp
@@ -19,39 +19,78 @@
  *
  */
 #include "QueuePolicy.h"
+#include "Queue.h"
 #include "qpid/framing/FieldValue.h"
+#include "qpid/framing/reply_exceptions.h"
+#include "qpid/log/Statement.h"
 
 using namespace qpid::broker;
 using namespace qpid::framing;
 
-QueuePolicy::QueuePolicy(uint32_t _maxCount, uint64_t _maxSize) : 
-    maxCount(_maxCount), maxSize(_maxSize), count(0), size(0) {}
-
-QueuePolicy::QueuePolicy(const FieldTable& settings) :
-    maxCount(getInt(settings, maxCountKey, 0)), 
-    maxSize(getInt(settings, maxSizeKey, defaultMaxSize)), count(0), size(0) {}
+QueuePolicy::QueuePolicy(uint32_t _maxCount, uint64_t _maxSize, const std::string& _type) : 
+    maxCount(_maxCount), maxSize(_maxSize), type(_type), count(0), size(0), policyExceeded(false) {}
 
 void QueuePolicy::enqueued(uint64_t _size)
 {
-    if (maxCount) count++;
+    if (maxCount) ++count;
     if (maxSize) size += _size;
 }
 
 void QueuePolicy::dequeued(uint64_t _size)
 {
-    if (maxCount) count--;
+    if (maxCount) --count;
     if (maxSize) size -= _size;
 }
 
-bool QueuePolicy::limitExceeded()
+bool QueuePolicy::checkLimit(const QueuedMessage& m)
+{
+    bool exceeded = (maxSize && (size.get() + m.payload->contentSize()) > maxSize) || (maxCount && (count.get() + 1) > maxCount);
+    if (exceeded) {
+        if (!policyExceeded) {
+            policyExceeded = true;
+            QPID_LOG(info, "Queue size exceeded policy for " << m.queue->getName());
+        }
+    } else {
+        if (policyExceeded) {
+            policyExceeded = false;
+            QPID_LOG(info, "Queue size within policy for " << m.queue->getName());
+        }
+    }
+    return !exceeded;
+}
+
+void QueuePolicy::tryEnqueue(const QueuedMessage& m)
+{
+    if (checkLimit(m)) {
+        enqueued(m);
+    } else {
+        std::string queue = m.queue ? m.queue->getName() : std::string("unknown queue");
+        throw ResourceLimitExceededException(
+            QPID_MSG("Policy exceeded on " << queue << " by message " << m.position 
+                     << " of size " << m.payload->contentSize() << " , policy: " << *this));
+    }
+}
+
+void QueuePolicy::enqueued(const QueuedMessage& m)
+{
+    enqueued(m.payload->contentSize());
+}
+
+void QueuePolicy::dequeued(const QueuedMessage& m)
+{
+    dequeued(m.payload->contentSize());
+}
+
+bool QueuePolicy::isEnqueued(const QueuedMessage&)
 {
-    return (maxSize && size > maxSize) || (maxCount && count > maxCount);
+    return true;
 }
 
 void QueuePolicy::update(FieldTable& settings)
 {
     if (maxCount) settings.setInt(maxCountKey, maxCount);
-    if (maxSize) settings.setInt(maxSizeKey, maxSize);    
+    if (maxSize) settings.setInt(maxSizeKey, maxSize);
+    settings.setString(typeKey, type);
 }
 
 
@@ -62,6 +101,17 @@ int QueuePolicy::getInt(const FieldTable& settings, const std::string& key, int
     else return defaultValue;
 }
 
+std::string QueuePolicy::getType(const FieldTable& settings)
+{
+    FieldTable::ValuePtr v = settings.get(typeKey);
+    if (v && v->convertsTo<std::string>()) {
+        std::string t = v->get<std::string>();
+        transform(t.begin(), t.end(), t.begin(), tolower);        
+        if (t == REJECT || t == FLOW_TO_DISK || t == RING || t == RING_STRICT) return t;
+    }
+    return REJECT;
+}
+
 void QueuePolicy::setDefaultMaxSize(uint64_t s)
 {
     defaultMaxSize = s;
@@ -69,20 +119,123 @@ void QueuePolicy::setDefaultMaxSize(uint64_t s)
 
 const std::string QueuePolicy::maxCountKey("qpid.max_count");
 const std::string QueuePolicy::maxSizeKey("qpid.max_size");
+const std::string QueuePolicy::typeKey("qpid.policy_type");
+const std::string QueuePolicy::REJECT("reject");
+const std::string QueuePolicy::FLOW_TO_DISK("flow_to_disk");
+const std::string QueuePolicy::RING("ring");
+const std::string QueuePolicy::RING_STRICT("ring_strict");
 uint64_t QueuePolicy::defaultMaxSize(0);
 
+FlowToDiskPolicy::FlowToDiskPolicy(uint32_t _maxCount, uint64_t _maxSize) : 
+    QueuePolicy(_maxCount, _maxSize, FLOW_TO_DISK) {}
+
+bool FlowToDiskPolicy::checkLimit(const QueuedMessage& m)
+{
+    return QueuePolicy::checkLimit(m) || m.queue->releaseMessageContent(m);
+}
+
+RingQueuePolicy::RingQueuePolicy(uint32_t _maxCount, uint64_t _maxSize, const std::string& _type) : 
+    QueuePolicy(_maxCount, _maxSize, _type), strict(_type == RING_STRICT) {}
+
+void RingQueuePolicy::enqueued(const QueuedMessage& m)
+{
+    QueuePolicy::enqueued(m);
+    qpid::sys::Mutex::ScopedLock l(lock);
+    queue.push_back(m);
+}
+
+void RingQueuePolicy::dequeued(const QueuedMessage& m)
+{
+    qpid::sys::Mutex::ScopedLock l(lock);
+    QueuePolicy::dequeued(m);
+    //find and remove m from queue
+    for (Messages::iterator i = queue.begin(); i != queue.end() && m.position <= i->position; i++) {
+        if (i->position == m.position) {
+            queue.erase(i);
+            break;
+        }
+    }
+}
+
+bool RingQueuePolicy::isEnqueued(const QueuedMessage& m)
+{
+    qpid::sys::Mutex::ScopedLock l(lock);
+    //for non-strict ring policy, a message can be dequeued before acked; need to detect this
+    for (Messages::iterator i = queue.begin(); i != queue.end() && m.position <= i->position; i++) {
+        if (i->position == m.position) {
+            return true;
+        }
+    }
+    return false;
+}
+
+bool RingQueuePolicy::checkLimit(const QueuedMessage& m)
+{
+    if (QueuePolicy::checkLimit(m)) return true;//if haven't hit limit, ok to accept
+    
+    QueuedMessage oldest;
+    {
+        qpid::sys::Mutex::ScopedLock l(lock);
+        oldest = queue.front();
+    }
+    if (oldest.queue->acquire(oldest) || !strict) {
+        qpid::sys::Mutex::ScopedLock l(lock);
+        if (oldest.position == queue.front().position) {
+            queue.pop_front();
+            QPID_LOG(debug, "Ring policy triggered in queue " 
+                     << (m.queue ? m.queue->getName() : std::string("unknown queue"))
+                     << ": removed message " << oldest.position << " to make way for " << m.position);
+        }
+        return true;
+    } else {
+        QPID_LOG(debug, "Ring policy could not be triggered in queue " 
+                 << (m.queue ? m.queue->getName() : std::string("unknown queue")) 
+                 << ": oldest message (seq-no=" << oldest.position << ") has been delivered but not yet acknowledged or requeued");
+        //in strict mode, if oldest message has been delivered (hence
+        //cannot be acquired) but not yet acked, it should not be
+        //removed and the attempted enqueue should fail
+        return false;
+    }
+}
+
+std::auto_ptr<QueuePolicy> QueuePolicy::createQueuePolicy(const qpid::framing::FieldTable& settings)
+{
+    uint32_t maxCount = getInt(settings, maxCountKey, 0);
+    uint32_t maxSize = getInt(settings, maxSizeKey, defaultMaxSize);
+    if (maxCount || maxSize) {
+        return createQueuePolicy(maxCount, maxSize, getType(settings));
+    } else {
+        return std::auto_ptr<QueuePolicy>();
+    }
+}
+
+std::auto_ptr<QueuePolicy> QueuePolicy::createQueuePolicy(uint32_t maxCount, uint64_t maxSize, const std::string& type)
+{
+    if (type == RING || type == RING_STRICT) {
+        return std::auto_ptr<QueuePolicy>(new RingQueuePolicy(maxCount, maxSize, type));
+    } else if (type == FLOW_TO_DISK) {
+        return std::auto_ptr<QueuePolicy>(new FlowToDiskPolicy(maxCount, maxSize));
+    } else {
+        return std::auto_ptr<QueuePolicy>(new QueuePolicy(maxCount, maxSize, type));
+    }
+
+}
+
+
 namespace qpid {
     namespace broker {
 
 std::ostream& operator<<(std::ostream& out, const QueuePolicy& p)
 {
-    if (p.maxSize) out << "size: max=" << p.maxSize << ", current=" << p.size;
-    else out << "size unlimited, current=" << p.size;
+    if (p.maxSize) out << "size: max=" << p.maxSize << ", current=" << p.size.get();
+    else out << "size: unlimited";
     out << "; ";
-    if (p.maxCount) out << "count: max=" << p.maxCount << ", current=" << p.count;
-    else out << "count unlimited, current=" << p.count;    
+    if (p.maxCount) out << "count: max=" << p.maxCount << ", current=" << p.count.get();
+    else out << "count: unlimited";    
+    out << "; type=" << p.type;
     return out;
 }
 
     }
 }
+